Unsupervised Image Segmentation using the Deffuant-Weisbuch Model from Social Dynamics

Unsupervised image segmentation algorithms aim at identifying disjoint homogeneous regions in an image, and have been subject to considerable attention in the machine vision community. In this paper, a popular theoretical model with it's origins in statistical physics and social dynamics, known as the Deffuant-Weisbuch model, is applied to the image segmentation problem. The Deffuant-Weisbuch model has been found to be useful in modelling the evolution of a closed system of interacting agents characterised by their opinions or beliefs, leading to the formation of clusters of agents who share a similar opinion or belief at steady state. In the context of image segmentation, this paper considers a pixel as an agent and it's colour property as it's opinion, with opinion updates as per the Deffuant-Weisbuch model. Apart from applying the basic model to image segmentation, this paper incorporates adjacency and neighbourhood information in the model, which factors in the local similarity and smoothness properties of images. Convergence is reached when the number of unique pixel opinions, i.e., the number of colour centres, matches the pre-specified number of clusters. Experiments are performed on a set of images from the Berkeley Image Segmentation Dataset and the results are analysed both qualitatively and quantitatively, which indicate that this simple and intuitive method is promising for image segmentation. To the best of the knowledge of the author, this is the first work where a theoretical model from statistical physics and social dynamics has been successfully applied to image processing.Comment: This paper is under consideration at Signal Image and Video Processing journa

Superpolynomial lower bounds for general homogeneous depth 4 arithmetic circuits

In this paper, we prove superpolynomial lower bounds for the class of homogeneous depth 4 arithmetic circuits. We give an explicit polynomial in VNP of degree $n$ in $n^2$ variables such that any homogeneous depth 4 arithmetic circuit computing it must have size $n^{\Omega(\log \log n)}$. Our results extend the works of Nisan-Wigderson [NW95] (which showed superpolynomial lower bounds for homogeneous depth 3 circuits), Gupta-Kamath-Kayal-Saptharishi and Kayal-Saha-Saptharishi [GKKS13, KSS13] (which showed superpolynomial lower bounds for homogeneous depth 4 circuits with bounded bottom fan-in), Kumar-Saraf [KS13a] (which showed superpolynomial lower bounds for homogeneous depth 4 circuits with bounded top fan-in) and Raz-Yehudayoff and Fournier-Limaye-Malod-Srinivasan [RY08, FLMS13] (which showed superpolynomial lower bounds for multilinear depth 4 circuits). Several of these results in fact showed exponential lower bounds. The main ingredient in our proof is a new complexity measure of {\it bounded support} shifted partial derivatives. This measure allows us to prove exponential lower bounds for homogeneous depth 4 circuits where all the monomials computed at the bottom layer have {\it bounded support} (but possibly unbounded degree/fan-in), strengthening the results of Gupta et al and Kayal et al [GKKS13, KSS13]. This new lower bound combined with a careful "random restriction" procedure (that transforms general depth 4 homogeneous circuits to depth 4 circuits with bounded support) gives us our final result

Religious Minorities and Provision of Public Goods: Evidence from Rural West Bengal

Religious and ethnic minorities across the world face partisan treatment with regard to provision of public goods, either as outcome of discriminatory practices or due to historical antecedents, such as the caste and religious divides in India. In several districts of West Bengal in India concentration of religious minorities, namely Muslims is higher than state and country-level averages. We measures access to public goods in rural West Bengal for different strata of minority concentration. Using Least Square, Generalized Linear Models and Blinder-Oaxaca decomposition, we find evidence of strong horizontal inequality against Muslims in terms of access to public goods. Blinder-Oaxaca decomposition shows that Muslims in larger concentrations face poorer access to infrastructure, health and transport facilities.religious minorities, public good, discrimination, welfare, West Bengal

The evolution of the mitochondrial genomes of calcareous sponges and cnidarians

The mitochondrial DNA (mtDNA) in animals (Metazoa) is a favorite molecule for phylogenetic studies given its relative uniformity in both size and organization. Yet, as the depth coverage of representative animal groups increases sharply thanks to recent advances in sequencing technology, some clades remain stubbornly under sampled, if even represented at all. Difficulties associated with data collection from problematic taxa can arise from highly derived sequences, fragmented genomes, unusual structure, or any combination of these. Particularly illustrative examples are found in non-bilaterian animals (placozoans, sponges, cnidarians, comb jellies) where the mtDNA is more variable in size and structure. The present dissertation provides several case studies of what is considered “unusual” mtDNA for animals. First, we describe some unusual characteristics of the mitochondrial genomes found in calcareous sponges (Calcarea, Porifera), where one, potentially two, novel genetic codes are inferred, transfer RNAs (tRNAs) are edited, and ribosomal RNA (rRNA) genes are in pieces. We also hypothesize that the mtDNA is linear and multipartite. Then, we explore the evolution of the mtDNA in medusozoan cnidarians (Medusozoa, Cnidaria). The mtDNA in Medusozoa is linear, and encodes two extra protein genes (lost in one clade) putatively involved in the maintenance and replication of the linear chromosomes. In addition, secondary segmentalization has occurred independently in some hydras (Hydridae) and box jellies (Cubozoa). Using the sequences from these mito-genomes, we propose a new phylogeny for Cnidaria, providing additional support for the clade [Medusozoa + Octocorallia], rendering Anthozoa (Hexacorallia + Octocorallia) paraphyletic. Finally, this dissertation concludes by a mini review stating the current state of knowledge of metazoan mtDNA and some of the pitfalls in the field of mitogenomics. In particular, the new findings further challenge the classical idea of a uniform mtDNA organization (frozen genome) in animals, and question any directional explanation of the evolution of the mtDNA in animals

Design and Noise Analysis of a Novel Auto-Zeroing Structure for Continuous-Time Instrumentation Amplifiers

This paper introduces a low-noise, low-power amplifier for high-impedance sensors. An innovative circuit using an auto-zeroed architecture combined with frequency modulation to reject offset and low-frequency noise is proposed and analysed. Special care was given to avoid broadband noise aliasing and chopping in the signal path, and to minimize both the resulting equivalent input offset voltage and equivalent input biasing current. The theoretical noise analysis of the proposed topology covers most of the noise sources of the circuit. Simulations show that the input-referred noise level of the circuit is 13.4nV/pHz for a power consumption of 85μA with a power supply from 1.8V to 3.6V

Dosimétrie clinique en radiothérapie moléculaire

La radiothérapie moléculaire (RTM) est une radiothérapie systémique, où le produit radiopharmaceutique se lie spécifiquement sur les tumeurs pour détruire sélectivement les cibles cancéreuses tout en préservant les organes sains. Lutathera® (177Lu-DOTATATE) est un radiopharmaceutique récemment approuvé par la FDA/EMA pour le traitement des tumeurs neuroendocrines gastro-entéro-pancréatiques (GEP-NETs). Dans la pratique clinique, les patients reçoivent une activité fixe de Lutathera®, 4 cycles de 7,4 GBq, en supposant que la pharmacocinétique du radiopharmaceutique est même entre les patients. La dosimétrie spécifique au patient permet un changement de paradigme majeur dans l'administration de la RTM, passant d'une approche "taille unique" à une véritable médecine personnalisée où l'activité administrée est évaluée spécifiquement sur la base de l'irradiation délivrée à chaque patient. Pour ce faire, il faut généralement déterminer la distribution spatiale du radiopharmaceutique dans les organes par imagerie à différents moments (imagerie quantitative), estimer le nombre total de désintégrations radioactives en intégrant l'activité dans le temps (évaluation pharmacocinétique) et calculer la dose absorbée à partir des caractéristiques physiques du radionucléide et du transport de l'énergie dans les tissus du patient. Actuellement, il n'existe pas de procédures normalisées pour effectuer la dosimétrie clinique. En outre, l'évaluation des incertitudes associées à la procédure de dosimétrie n'est pas triviale. Le projet DosiTest a été lancé pour évaluer les incertitudes associées à chacune des étapes du flux de travail de la dosimétrie clinique, via une inter-comparaison multicentrique basée sur la modélisation de Monte Carlo (MC). La première phase de la thèse a consisté à comparer les analyses dosimétriques effectuées par différents centres utilisant le même logiciel et le même protocole sur le même ensemble de données de patients dans le cadre du projet IAEA-CRP E23005 afin d'évaluer la précision de la dosimétrie clinique. À notre connaissance, c'est la première fois qu'une comparaison dosimétrique multicentrique d'un seul ensemble de données cliniques sur un patient a été entreprise en utilisant le même protocole et le même logiciel par de nombreux centres dans le monde entier. Elle a mis en évidence le besoin crucial d'établir des points de contrôle et d'effectuer des vérifications de bon sens pour éliminer les disparités significatives entre les résultats et distinguer les pratiques erronées de la variabilité inter-opérateurs acceptable. Un résultat important de ce travail a été le manque d'assurance qualité en dosimétrie de médecine nucléaire clinique et la nécessité de développer des procédures de contrôle qualité. Alors que la dosimétrie gagne en popularité en médecine nucléaire, les meilleures pratiques doivent être adoptées pour garantir la fiabilité, la traçabilité et la reproductibilité des résultats. Cela met également en avant la nécessité de dispenser une formation suffisante après l'acquisition des progiciels relativement nouveaux, au-delà de quelques jours. Ceci est clairement insuffisant dans le contexte d'un domaine émergent où l'expérience professionnelle fait souvent défaut. Ensuite, l'étude de l'exactitude de la dosimétrie clinique nécessite de générer des ensembles de données de test, afin de définir la vérité de base par rapport à laquelle les procédures de dosimétrie clinique peuvent être comparées. La deuxième section de la thèse traite de la simulation de l'imagerie TEMP scintigraphique tridimensionnelle en implémentant le mouvement du détecteur d'auto-contournement dans la boîte à outils Monte Carlo GATE. Après la validation des projections TEMP/TDM sur des modèles anthropomorphes, une série d'images réalistes de patients cliniques a été générée. La dernière partie de la thèse a établi la preuve de concept du projet DosiTest, en utilisant un ensemble de données TEMP/TDM virtuelles (simulées) à différents moments, avec différentes gamma-caméras, permettant de comparer différentes techniques dosimétriques et d'évaluer la faisabilité clinique du projet dans certains départements de médecine nucléaire.Molecular radiotherapy (MRT) is a systemic radiotherapy where the radiopharmaceutical binds specifically to tumours to selectively destroy cancer targets while sparing healthy organs. Lutathera® (177Lu-DOTATATE) is a radiopharmaceutical that was recently FDA/EMA approved for the treatment of the GastroEnteroPancreatic NeuroEndocrine Tumours (GEP-NETs). In clinical practice, patients are administered with a fixed activity of Lutathera®, assuming that radiopharmaceutical distribution is the same for all patients. Patient-specific dosimetry allows for a major paradigm shift in the administration of MRT from "one-size-fits-all" approach, to real personalised medicine where administered activity is assessed specifically on the base of the irradiation delivered to each patient. This usually requires determining the spatial distribution of the radiopharmaceutical in various organs via imaging at different times (quantitative imaging), estimating the total number of radioactive decays by integrating activity over time (pharmacokinetic assessment) and calculating the absorbed dose using the physical characteristics of the radionuclide and implementing radiation transport in patient's tissues. Currently, there are no standardised procedures to perform clinical dosimetry. In addition, the assessment of the uncertainties associated with the dosimetry procedure is not trivial. The DosiTest project (http://www.dositest.org/) was initiated to evaluate uncertainties associated with each of the steps of the clinical dosimetry workflow, via a multicentric inter-comparison based on Monte Carlo (MC) modelling. The first phase of the thesis compared dosimetry analysis performed by various centres using the same software and protocol on the same patient dataset as a part of IAEA-CRP E23005 project in order to appraise the precision of clinical dosimetry. To our knowledge, this is the first time that a multi-centric dosimetry comparison of a single clinical patient dataset has been undertaken using the same protocol and software by many centres worldwide. It highlighted the critical need to establish checkpoints and conduct sanity checks to eliminate significant disparities among results, and distinguish erroneous practice with acceptable inter-operator variability. A significant outcome of this work was the lack of quality assurance in clinical nuclear medicine dosimetry and the need for the development of quality control procedures. While dosimetry is gaining popularity in nuclear medicine, best practices should be adopted to ensure that results are reliable, traceable, and reproducible. It also brings forward the need to deliver sufficient training after the acquisition of the relatively new software packages beyond a couple of days. This is clearly insufficient in a context of an emerging field where the professional experience is quite often lacking. Next, the study of clinical dosimetry accuracy requires generating test datasets, to define the ground truth against which clinical dosimetry procedures can be benchmarked. The second section of the thesis addressed the simulation of three-dimensional scintigraphic SPECT imaging by implementing auto-contouring detector motion in the GATE Monte Carlo toolkit. Following the validation of SPECT/CT projections on anthropomorphic models, a series of realistic clinical patient images were generated. The last part of the thesis established the proof of concept of the DosiTest project, using a virtual (simulated) SPECT/CT dataset at various time points, with various gamma cameras, enabling comparison of various dosimetric techniques and to assess the clinical feasibility of the project in selected nuclear medicine departments

Application of PV Panels in Large Multi-Story Buildings

Application of PV Panels in Large Multi-Story Buildings Feasibility Study Sara Kayal The awareness of global warming along with an ever increasing demand for a new source of energy has brought a strong interest in harnessing natural resources such as solar energy. This thesis evaluates the viability of applying photovoltaic (PV) panels in high-rise commercial buildings of around 20 stories. Specifically, the thesis is intended to provide a pre-planning tool during the early design stage for architects and designers who are considering the deployment of PV panels in new multi-story construction. The first three chapters cover a comprehensive literature review and describe several case studies of the application of PV panels in multi-story buildings. The first chapter serves as an introduction to the objectives and rationale of PV panel research. Chapter 2 explains the physics and characteristics of PV panel technology that is applicable to multi-story buildings. Various PV panel types are explored in this chapter and it is suggested that window-based PV panels are the most suitable type for multi-story buildings in which the available roof area is small in area and limited in flexibility due to competition with other uses. Chapter 3 investigates factors that influence the efficiency of PV panels. These factors reduce the efficiency of PV panels to about 10-15%. In Chapter 4 a study model is presented to validate the results of the previous chapters and to determine the feasibility of PV panel systems with the aid of computer model analysis and simulation. The study model includes a base case of a 20-story building that is surrounded by four adjacent buildings, one adjacent to each orientation. Five configurations of the base model with different arrangements of PV panels were analyzed. First, electrical energy of the base case was calculated without applying any PV panels. The second and third configurations include PV panels on all of the available façade areas on a typical summer and winter day, respectively. The fourth and fifth configurations feature PV panels on only the top 10 floors. The simulation results show that although some savings accrue over a 25-year life-cycle period, these savings pale in comparison with the initial capital cost associated with the purchase and installation of the PV panels. It was also found that although crystalline silicon panels have a higher initial cost, their superior efficiency and performance present them as better candidates for PV panel applications. In addition, as expected, the south orientation provides potentially the largest amount of electricity production. In Chapter 5 the simulation results are summarized. The simulation studies address the application of PV panels from three different perspectives, namely: economics; technical feasibility; and, subjective factors. The first four chapters confirm that PV panels, at the current level of technology, are not an efficient and cost effective solution for multi-story buildings. They can satisfy only a very small portion of the electrical energy demand of the building at a very high initial capital cost. However, some strategies are suggested for mitigating the dual problems of inadequate PV production volume and high initial costs. Subjective factors account for other benefits that are not related to economic considerations. These factors include educational, promotional, and business line promotion benefits that could accrue to the building owner